That back leg move is like a shortstop going in the hole and making the throw to first with a mid air jump. It can be done but if you could plant and get momentum and weight transfer to the front side it would be more desirable and more powerful. The movements are correct and Teacherman is onto something as a drill to promote correct movements. Certainly he doesn't espouse hitting while standing on your back leg.
Is anybody here promoting a "jump throw" type of swing just because it's possible?
Asking me? Not sure. I don’t advocate any jumping when hitting.